Fix P0113: Mechanic’s Solutions That WORKED!

The OBD2 code P0113 is identified when the Intake Air Temperature (IAT) Sensor Circuit sends a signal that is too high, suggesting the air entering the engine is hotter than it realistically is. This condition can cause the engine’s computer to miscalculate the air-fuel mixture, potentially leading to issues such as hard shifting, high idle, or stalling. This code points towards electrical issues within the sensor circuit or the sensor itself.

P0113 quick overview

Meaning	P0113: Intake Air Temperature Sensor Circuit High Input
Is it serious?	Yes, it can cause noticeable drivability issues and should be addressed promptly.
Possible causes	– Faulty IAT sensor – Short to power in the IAT sensor circuit – Corrosion or poor connection at the IAT sensor connector – Faulty Engine Control Module (ECM)
How to diagnose?	Check the IAT sensor and connector for damage or corrosion. Inspect the wiring for shorts to power, which could cause the high input signal. Test the IAT sensor’s voltage to ensure it aligns with the expected values. Review the ECM for any potential faults or the need for an update. Replace the IAT sensor or wiring harness if defects are found.

How to fix P0113 – learn from mechanics

I looked into P0113 service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: Pontiac

Vehicle Information 2001 Pontiac Grand Am GT 3.4L

Issue + Repair History

• Complaint of MIL lamp on with code P0113
• Replaced IAT sensor on the air hose duct with three different sensors, but check engine light comes back on
• After clearing codes, runs fine for 5 miles, then check engine light returns with code P0113 and shifts hard

Other OBD2 Codes + Test Results

• Error code: P0113 (IAT voltage low)

Mechanic Suggestions

• Check for broken wires at the connector; pull slightly on wires, and if one feels elastic, it indicates a broken wire inside the conduit
• Check the transmission fluid level with the car running by removing the bolt from the passenger side axle shaft housing; fluid should flow from the hole when full
• Replace the connector for the IAT sensor, as broken wires in the harness are a common problem; cut the harness back to ensure the broken part is replaced
• Use a symptom diagnosis chart for the P0113 code to explore other possible causes
• Replace the IAT harness pigtail with a new one, as wires inside the insulation can work harden and break due to engine vibrations

Final Fix

• Replacing the pigtail connector for the IAT sensor resolved the issue.

Case #2: GMC

Vehicle Information 1998 GMC Safari SL 4.3L

Issue + Repair History

• Complaint of high idle at 3500rpm, remains high regardless of engine temperature
• Error code: P0113 (idle air temperature)
• Intake temperature shows as -40°F on scan tool
• Replaced idle air control (IAC) and intake air temperature (IAT) sensor
• Throttle body plate and revet checked, found okay
• Replaced IAC motor with new Delco unit and reset it with scan tool, but no change in idle speed

Other OBD2 Codes + Test Results

• Error code: P0113 (idle air temperature)
• All fuses checked okay
• Computer wires checked okay

Mechanic Suggestions

• Check IAC counts; if at 0 during high idle, check for vacuum leak; if counts are high, inspect wiring for rubbing or shorting near PCM, which is typically located under the master cylinder
• Investigate coolant temperature sensor; though unlikely to cause such high idle, it’s worth checking
• Consider the possibility of two separate issues: for DTC P0113, suspect bad connection, wiring issues, or PCM; for high idle, suspect vacuum leak, potentially from a leaky throttle body gasket
• Open circuit at -40°F indicates a wiring issue; inspect for broken wires near the battery or PCM
• Look for vacuum leaks and ensure the cruise control cable is not hanging, as these could also contribute to high idle

Final Fix

• The problem was identified as a broken wire near the battery, affecting the PCM’s ability to control the idle speed. After repairing the wire, the issue was resolved.

Case #3: Ford

Vehicle Information 2004 Ford E-350 Super Duty 5.4L

Issue + Repair History

• Complaint of stalling at highway speeds, but issue not duplicated during test drive
• Check engine light was on, codes retrieved: P0102, P0113, P1100, P1112
• Cleared all codes; only P0113 returned
• PCV hose inspected and found in good condition

Other OBD2 Codes + Test Results

• Error codes: P0102, P0113, P1100, P1112
• Long-term fuel trim: -19%
• MAF sensor readings: 2.65 G/S at idle, 0.01 volts at idle
• IAT sensor reading: 3.61 volts at idle

Mechanic Suggestions

• Check MAF sensor; it may need cleaning with electronic parts cleaner or replacement
• Investigate the coil pack, plugs, and wires for potential issues such as carbon tracking
• Ensure the MAF sensor voltage at idle is around one volt; if no voltage is detected at the sensor or PCM, consider replacing the MAF sensor
• MAF sensor should ideally have a reading of 0.6 – 0.9 volts at idle; inspect for broken wires and contamination on sensor elements

Final Fix

• The issue was resolved by replacing the MAF sensor. The optimal readings for the MAF sensor were found to be 1.0 volts and 7-19 G/S, confirming the sensor replacement as the solution.

Diagnostic Step	Brief Explanation
Inspect IAT sensor and connector	Look for any physical damage or signs of corrosion that might impair the sensor’s functionality.
Check wiring for shorts	Examine the IAT sensor’s wiring for any shorts to power, which could cause incorrect voltage readings.
Test sensor voltage	Measure the voltage at the IAT sensor to verify it is within the normal range specified by the manufacturer.
Review ECM operation	Consider whether the ECM itself might be faulty or require an update to correct the sensor reading issue.
Replace defective components	If any issues are found with the IAT sensor or wiring harness, replace them to restore normal operation.